Background and purpose
Mild cognitive impairment (MCI) is associated with pronounced grey matter atrophy in various brain regions. However, the association between atrophy patterns and progression ...from no cognitive impairment (NCI) to Parkinson's disease (PD)‐MCI is not clearly known. We investigated the pattern and progression of atrophy in subcortical structures and its impact on cognition in patients with mild PD.
Methods
Sixty‐five patients with mild PD with baseline and longitudinal clinical and neuropsychological assessments, and structural magnetic resonance imaging scans were studied. Movement Disorder Society Task Force criteria were used to classify patients with PD into PD‐NCI (n = 54) and PD‐MCI (n = 11). Based on progression over time, those who remained without cognitive impairment were classified as PD‐stable (n = 42) and those who converted to MCI over 18 months were classified as PD‐converters (n = 12). FreeSurfer was used to measure cortical thickness and subcortical volumes at baseline and follow‐up.
Results
Parkinson's disease‐MCI showed baseline thalamus atrophy and progressive atrophy in the thalamus, caudate, presubiculum, cornu ammonis 1 and 2–3, and significant memory and executive dysfunction compared with PD‐NCI. PD‐converters had greater accumbens atrophy at baseline and progressive atrophy in the thalamus, caudate and accumbens with dysfunctions in memory and executive domains.
Conclusions
Progression of cognitive impairment in non‐demented PD is associated with a specific pattern of subcortical atrophy. Findings from this study will allow future studies to investigate in the role of subcortical structures as a biomarker for PD dementia.
Suspended particle devices (SPDs) adapted for controlling the transmission of electromagnetic radiation have become an area of considerable focus for smart window technology due to their desirable ...properties, such as instant and precise light control and cost-effectiveness. Here, we demonstrate a SPD with tunable transparency in the visible regime using colloidal assemblies of nanoparticles. The observed transparency using ZnS/SiO2 core/shell colloidal nanoparticles is dynamically tunable in response to an external electric field with increased transparency when applied voltage increases. The observed transparency change is attributed to structural ordering of nanoparticle assemblies and thereby modifies the photonic band structures, as confirmed by the finite-difference time-domain simulations of Maxwell’s equations. The transparency of the device can also be manipulated by changing the particle size and the device thickness. In addition to transparency, structural colorations and their dynamic tunability are demonstrated using α-Fe2O3/SiO2 core/shell nanomaterials, resulting from the combination of inherent optical properties of α-Fe2O3/SiO2 nanomaterials and coloration due to their tunable structural particle assemblies in response to electric stimuli.
Recent advancements with the directed assembly of block copolymers have enabled the fabrication over cm2 areas of highly ordered metal nanowire meshes, or nanolattices, which are of significant ...interest as transparent electrodes. Compared to randomly dispersed metal nanowire networks that have long been considered the most promising next-generation transparent electrode material, such ordered nanolattices represent a new design paradigm that is yet to be optimized. Here, through optical and electrical simulations, we explore the potential design parameters for such nanolattices as transparent conductive electrodes, elucidating relationships between the nanowire dimensions, defects, and the nanolattices’ conductivity and transmissivity. We find that having an ordered nanowire network significantly decreases the length of nanowires required to attain both high transmissivity and high conductivity, and we quantify the network’s tolerance to defects in relation to other design constraints. Furthermore, we explore how both optical and electrical anisotropy can be introduced to such nanolattices, opening an even broader materials design space and possible set of applications.
Formation of biomineral structures is increasingly attributed to directed growth of a mineral phase from an amorphous precursor on an organic matrix. While many in vitro studies have used calcite ...formation on organothiol self-assembled monolayers (SAMs) as a model system to investigate this process, they have generally focused on the stability of amorphous calcium carbonate (ACC) or maximizing control over the order of the final mineral phase. Little is known about the early stages of mineral formation, particularly the structural evolution of the SAM and mineral. Here we use near-edge X-ray absorption spectroscopy (NEXAFS), photoemission spectroscopy (PES), X-ray diffraction (XRD), and scanning electron microscopy (SEM) to address this gap in knowledge by examining the changes in order and bonding of mercaptophenol (MP) SAMs on Au(111) during the initial stages of mineral formation as well as the mechanism of ACC to calcite transformation during template-directed crystallization. We demonstrate that formation of ACC on the MP SAMs brings about a profound change in the morphology of the monolayers: although the as-prepared MP SAMs are composed of monomers with well-defined orientations, precipitation of the amorphous mineral phase results in substantial structural disorder within the monolayers. Significantly, a preferential face of nucleation is observed for crystallization of calcite from ACC on the SAM surfaces despite this static disorder.
This letter describes the synthesis and structural characterization of monolithic carbon aerogel (CA) materials that possess both high surface areas and hierarchical porosity. Thermal activation of a ...macroporous CA structure, one that was derived from an acetic acid-catalyzed sol–gel polymerization reaction, yields monolithic materials with large pore volumes and surface areas exceeding 3000
m
2/g. Given the flexibility of CA synthesis, this approach offers viability to engineer new materials for use as catalyst supports, electrodes, capacitors and sorbent systems.
Methanol photoreforming is an emerging and promising technology in harnessing solar energy to produce hydrogen as well as value-added by-products including formaldehyde (HCHO), formic acid (HCOOH), ...and methyl formate (HCOOCH3). Unlike photocatalytic water splitting, methanol (CH3OH) photoreforming has significantly lower reaction energy and clean water demand. Besides, methanol as the organic substrate with availability from industrial waste streams allows the potential collaboration of photoreforming plants with relevant waste treatment facilities. In harmonization with the expeditious research progress in methanol photoreforming, this work provides an extensive review from the perspectives of reaction mechanisms and photocatalyst systems, as well as modification techniques including co-catalyst loading and heterojunctions or Z-schemes formation in endowing performance enhancement. Ultimately, this work aims to provide insight, notably into the rational engineering of photocatalytic materials, which would spearhead future development. The prospect and challenges in this field are put forward to empower collective efforts in paving a sustainable and efficient technology.
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•The overall mechanism of methanol photoreforming is presented.•Selection criteria of photocatalyst for methanol photoreforming are outlined.•Various photocatalyst groups are discussed, with their limitations.•Modifications including co-catalyst loading and composites formation are reviewed.
In this paper, Cu–20vol%NbC composite was prepared by in situ and ex situ processing methods. In in situ method, a mixture of Cu–Nb–C was mechanically alloyed in a high energy planetary mill while in ...ex situ method, a mixture of Cu–NbC powder was mixed in a low energy ball mill. Consolidation of the composite powder was systematically studied by pressing the powder at different compaction pressures, i.e. in the range of 350–650
MPa, followed with sintering at 900
°C for an hour. The presence of the NbC particle in copper matrix of the Cu–Nb–C sintered sample has been confirmed by X-ray diffraction and energy dispersive X-ray analysis. In situ composite has higher hardness and electrical conductivity than its counterpart due to a homogenous distribution of fine NbC particle and good NbC–Cu adhesion bonding. Higher compaction pressure has increased the hardness, electrical conductivity and density of the composites.
We introduce the concept of marketing avoidance —consumer efforts to conceal themselves and to deflect marketing. The setting is one in which sellers market some item through solicitations to ...potential consumers, who differ in their benefit from the item and suffer harm from receiving solicitations. Concealment by one consumer induces sellers to shift solicitations to other consumers, whereas deflection does not. Solicitations cause two externalities: direct harm on consumers and the (indirect) cost of consumer concealment and deflection. We find that in markets where the marginal cost of solicitation is sufficiently low, efforts by low-benefit consumers to conceal themselves will increase the cost-effectiveness of solicitations and lead sellers to market more. However, concealment by high-benefit consumers leads sellers to market less. Furthermore, concealment by low-benefit consumers increases direct privacy harm, and consumer welfare is higher with deflection than concealment. Finally, it is optimal to impose a charge on solicitations.
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